Strip, and backlight unit and liquid crystal display including the same

ABSTRACT

Disclosed is a mold frame including a first guide defining the position of a photoconversion layer and at least one of optical sheets disposed on the photoconversion layer, a backlight unit and a liquid crystal display including the same, and the like. The first guide includes a first surface facing the liquid crystal panel, a second surface opposite to the first surface, and a third surface extended from the edge of the first surface to the edge of second surface, wherein at least a portion of the second surface is provided with a strip, and wherein the strip is extended along the edge of the optical sheet or the photoconversion layer to overlap a region adjacent to the edge of the top surface of the optical sheet or adjacent to the edge of the top surface of the photoconversion layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 14/833,722, filed on Aug. 24, 2015, which claimspriority to Korean Patent Application No. 10-2014-0109887 filed on Aug.22, 2014, and all the benefits accruing therefrom under 35 U.S.C. § 119,the content of which in its entirety is herein incorporated byreference.

BACKGROUND 1. Field

Disclosures relate to a strip to reduce light leakage, and a backlightunit and a liquid crystal display (“LCD”) including the strip.

2. Description of the Related Art

According to popularization of information equipment such as a portableterminal, display quality of flat panel display devices becomesimportant. In relation to this, vigorous researches have been made toenhance display quality of flat panel display devices by introducing aquantum dot sheet with a plurality of semiconductor nanocrystals (alsoknown as quantum dots) dispersed in a polymer host matrix into the flatpanel display devices.

The quantum dot is a semiconductor material having a crystallinestructure of a several nanometer size, and may have a high surface areaper unit volume due to small size thereof and may provide quantumconfinement effects. The quantum dot provides an energy-excited state byabsorbing light from an excitation source, and emits energycorresponding to the energy bandgap of the quantum dot. As the quantumdots may emit light of various colors depending on their size and thecomposition, the quantum dots may be effectively used as aphotoconversion layer in a flat panel display device such as a liquidcrystal display.

SUMMARY

A display including the quantum dot-included photoconversion sheet mayfrequently experience a light leakage phenomenon (e.g., a blue lightleakage phenomenon) at a display edge region, which may deteriorate thedisplay quality.

An embodiment provides a mold frame that decreases a light leakagephenomenon in a flat panel display and improves light uniformity.

Another embodiment provides a backlight unit including the mold frame.

Yet another embodiment provides a liquid crystal display including themold frame.

Further yet another embodiment provides a photoconversion sheet thatdecreases light leakage phenomenon and improves light uniformity.

According to an embodiment, a mold frame includes a first guide whichdefines a position of a photoconversion layer or a position of anoptical sheet disposed on the photoconversion layer, and a stripdisposed on the first guide, where the first guide includes a firstsurface defined to face a liquid crystal panel, a second surface opposedto the first surface, and a third surface extending from an edge offirst surface to an edge of second surface. In such an embodiment, thestrip is disposed on the second surface, and the strip contacts an edgeportion of a top surface of the optical sheet or an edge portion of atop surface of the photoconversion layer when the optical sheet or thephotoconversion layer is combined with the mold frame.

In an embodiment, the mold frame may further include a second guidedisposed on the first guide and which defines a position of the liquidcrystal panel. In an embodiment, the mold frame may further include athird guide disposed under the first guide and which further defines theposition of the photoconversion layer or the position of the opticalsheet.

In an embodiment, the first surface may support the liquid crystalpanel.

In an embodiment, the second surface may define a position of thephotoconversion layer, and the third surface may define the position ofthe optical sheet.

In an embodiment, the third surface may include a step, and an upperpart or a lower part of the step may define the position of the opticalsheet.

In an embodiment, the lower part of the step may protrude further thanthe upper part and support the bottom surface of the optical sheet.

In an embodiment, a bottom surface of the strip may face the edgeportion of the top surface of the photoconversion layer or the edgeportion of the top surface of the optical sheet.

In an embodiment, the strip may include at least one of: a filmincluding a polymer matrix and a light emitting material dispersed inthe polymer matrix, where the light emitting material includes asemiconductor nanocrystal, an inorganic phosphor, an organic dye or acombination thereof; a polymer film including a reflective film; and astacked film including a light scattering layer and a light adsorptionlayer stacked on the light scattering layer.

In an embodiment, the polymer matrix may include a thiol-ene resin, apoly(meth)acrylate resin, an epoxy resin, a silicone resin, a urethaneresin, or a combination thereof.

In an embodiment, the reflective film may include a specular reflectivefilm or a scattered reflective film.

In an embodiment, the light scattering layer may include a polymer layerincluding at least one selected from silica, alumina, glass, calciumcarbonate (CaCO₃), talc, mica, aluminum oxide, barium titanate, bariumcarbonate, barium sulfate, zinc oxide (ZnO), cerium oxide, titaniumoxide, zirconium oxide (ZrO₂), aluminum hydroxide and magnesium oxide(MgO), and the light absorption layer may include a polymer layerincluding carbon black, a black dye, a black pigment, iron oxide, copperoxide, tin oxide or a mixture thereof. In such an embodiment, the lightscattering layer may overlap the edge portion of the top surface of theoptical sheet or the edge portion of the top surface of thephotoconversion layer.

In an embodiment, the strip may cover an entire of the second surface.

In an embodiment, the strip may have a thickness of less than or equalto about 10 millimeters (mm).

According to another embodiment of the invention, a backlight unitincludes:

a light source which emits light;

a photoconversion layer spaced apart from the light source and whichconverts the light incident thereto from the light source to white lightand emits the white light; and

a strip overlapping an edge portion of the photoconversion layer.

In an embodiment, the strip may be a photoconversion strip.

In an embodiment, the photoconversion strip may contact the edge portionof the photoconversion layer.

In an embodiment, the backlight unit may further include an opticalsheet disposed over the photoconversion layer.

In an embodiment, the photoconversion strip may contact an edge portionof the optical sheet.

In an embodiment, the backlight unit may further include a mold frameand wherein the strip may be disposed between the mold frame and theedge portion of the photoconversion layer.

In an embodiment, the strip may be attached to the mold frame.

In an embodiment, the strip may be a photoconversion strip.

In an embodiment, the photoconversion strip may contact the edge portionof the photoconversion layer.

In an embodiment, the strip may include at least one of: a filmincluding a polymer matrix and a light emitting material dispersed inthe polymer matrix, where the light emitting material includes asemiconductor nanocrystal, an inorganic phosphor, an organic dye or acombination thereof; a polymer film including a reflective material; anda stacked film including a light scattering layer and a light absorptionlayer on the light scattering layer.

According to another embodiment of the invention, the liquid crystaldisplay includes:

a liquid crystal panel; and

a backlight unit which provides light to the liquid crystal panelwhereinthe backlight unit includes: a light source including a blue lightemitting diode; a photoconversion layer spaced apart from the lightsource and which converts light incident thereto from the light sourceto white light and emits the white light;

a strip overlapping an edge portion of a photoconversion layer.

In an embodiment, the strip may be a photoconversion strip.

In an embodiment, the photoconversion strip may contact the edge portionof the photoconversion layer.

In an embodiment, the liquid crystal display may further include anoptical sheet disposed over the photoconversion layer.

In an embodiment, the photoconversion strip may contact an edge portionof the optical sheet.

In an embodiment, the liquid crystal display may further include a moldframe and wherein the strip is disposed between the mold frame and theedge portion of the photoconversion layer.

In an embodiment, the strip may be attached to the mold frame.

In an embodiment, the strip may be a photoconversion strip.

In an embodiment, the photoconversion strip contacts the edge portion ofthe photoconversion layer.

In an embodiment, the strip includes at least one of: a film including apolymer matrix and a light emitting material dispersed in the polymermatrix, where the light emitting material includes a semiconductornanocrystal, an inorganic phosphor, an organic dye or a combinationthereof; a polymer film including a reflective film; and a stacked filmincluding a light scattering layer and a light absorption layer on thelight scattering layer.

According to another embodiment, a photoconversion sheet includes apolymer matrix and a light emitting material dispersed in the polymermatrix, where the light emitting material includes a semiconductornanocrystal, an inorganic phosphor, an organic dye or a combinationthereof, where a strip is disposed on a surface thereof along an edgeportion.

In an embodiment, the strip may protrude from the edge portion of thephotoconversion sheet to define a step structure.

In an embodiment, the strip may extend along an entire edge of thephotoconversion sheet.

In an embodiment, the strip may include at least one of: a filmincluding a polymer matrix and a light emitting material dispersed inthe polymer matrix, where the light emitting material includes asemiconductor nanocrystal, an inorganic phosphor, an organic dye or acombination thereof; a polymer film including a reflective material; anda stacked film including a light scattering layer and a light absorptionlayer on the light scattering.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the invention will become more apparentby describing in detailed exemplary embodiments thereof with referenceto the accompanying drawings, in which:

FIG. 1 is a schematic cross-sectional view of an embodiment of a moldframe;

FIG. 2 is a plain view illustrating the bottom of an embodiment of amold frame;

FIG. 3 is a schematic perspective view of an embodiment of a mold frame;

FIG. 4 is a schematic cross-sectional view of an embodiment of a moldframe according to the invention;

FIG. 5 is a schematic cross-sectional view of an embodiment of a moldframe;

FIG. 6 is a schematic cross-sectional view of an embodiment of abacklight unit including a mold frame;

FIG. 7 is a schematic cross-sectional view of an alternative embodimentof a backlight unit including a mold frame;

FIG. 8 is a schematic cross-sectional view of another alternativeembodiment of a backlight unit including a mold frame;

FIG. 9 is a schematic cross-sectional view of an embodiment of a liquidcrystal display including a mold frame;

FIG. 10 is a schematic cross-sectional view of an alternative embodimentof a liquid crystal display including a mold frame;

FIG. 11 is a schematic cross-sectional view of another alternativeembodiment of a liquid crystal display including a mold frame; and

FIG. 12 is a schematic cross-sectional view of an alternative embodimentof a mold frame.

DETAILED DESCRIPTION

Embodiments now will be described more fully hereinafter with referenceto the accompanying drawings. The operating principle may, however, beembodied in many different forms, and the inventive scope should not beconstrued as limited to the embodiments set forth herein. Rather, theseembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the operating principle to those skilledin the art. Like reference numerals refer to like elements throughout.

It will be understood that, although the terms “first,” “second,”“third” etc. may be used herein to describe various elements,components, regions, layers and/or sections, these elements, components,regions, layers and/or sections should not be limited by these terms.These terms are only used to distinguish one element, component, region,layer or section from another element, component, region, layer orsection. Thus, “a first element,” “component,” “region,” “layer” or“section” discussed below could be termed a second element, component,region, layer or section without departing from the teachings herein.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a,” “an,” and “the” are intended to include the pluralforms, including “at least one,” unless the content clearly indicatesotherwise. “Or” means “and/or.” As used herein, the term “and/or”includes any and all combinations of one or more of the associatedlisted items. It will be further understood that the terms “comprises”and/or “comprising,” or “includes” and/or “including” when used in thisspecification, specify the presence of stated features, regions,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,regions, integers, steps, operations, elements, components, and/orgroups thereof.

Furthermore, relative terms, such as “lower” or “bottom” and “upper” or“top,” may be used herein to describe one elements relationship toanother element as illustrated in the Figures. It will be understoodthat relative terms are intended to encompass different orientations ofthe device in addition to the orientation depicted in the Figures. Forexample, if the device in one of the figures is turned over, elementsdescribed as being on the “lower” side of other elements would then beoriented on “upper” sides of the other elements. The exemplary term“lower,” can therefore, encompasses both an orientation of “lower” and“upper,” depending on the particular orientation of the figure.Similarly, if the device in one of the figures is turned over, elementsdescribed as “below” or “beneath” other elements would then be oriented“above” the other elements. The exemplary terms “below” or “beneath”can, therefore, encompass both an orientation of above and below.

“About” or “approximately” as used herein is inclusive of the statedvalue and means within an acceptable range of deviation for theparticular value as determined by one of ordinary skill in the art,considering the measurement in question and the error associated withmeasurement of the particular quantity (i.e., the limitations of themeasurement system). For example, “about” can mean within one or morestandard deviations, or within ±30%, 20%, 10%, 5% of the stated value.

It will be understood that when an element such as a layer, film,region, or substrate is referred to as being “on” another element, itcan be directly on the other element or intervening elements may also bepresent. In contrast, when an element is referred to as being “directlyon” another element, there are no intervening elements present.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure belongs. It willbe further understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and thedisclosure, and will not be interpreted in an idealized or overly formalsense unless expressly so defined herein.

Exemplary embodiments are described herein with reference to crosssection illustrations that are schematic illustrations of idealizedembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, embodiments described herein should not beconstrued as limited to the particular shapes of regions as illustratedherein but are to include deviations in shapes that result, for example,from manufacturing. For example, a region illustrated or described asflat may, typically, have rough and/or nonlinear features. Moreover,sharp angles that are illustrated may be rounded. Thus, the regionsillustrated in the figures are schematic in nature and their shapes arenot intended to illustrate the precise shape of a region and are notintended to limit the scope of the claims.

Unless mentioned otherwise, “defining the position of a subject matter(e.g., a layer or a sheet)” in the specification refers to limiting themotion thereof toward a certain direction (e.g., up, down, left, right,or a combination thereof).

Hereinafter, embodiments will be described in detail with reference tothe accompanying drawings.

FIG. 1 is a schematic cross-sectional view of an embodiment of a moldframe. In an embodiment, the mold frame may be a mold frame of a liquidcrystal display device. According to an embodiment, the mold frameincludes a first guide A defining the positions of a photoconversionlayer (e.g. a photoconversion sheet) and an optical sheet (e.g., one ormore optical sheets) disposed on the photoconversion layer of the liquidcrystal display device. The mold frame may further include a secondguide B disposed on the first guide and defining the position of aliquid crystal panel of the liquid crystal display device. The moldframe may further include a third guide C disposed under the first guideand further defining the position of the photoconversion sheet or theoptical sheet.

Referring to FIG. 1, the first guide A has a first surface defined toface the liquid crystal panel and a second surface opposite to the firstsurface. The first guide has a third surface extending from an edge offirst surface toward an edge of second surface. In such an embodiment, afixing member may be provided on the first surface for fixing theposition of an optical sheet and/or a liquid crystal panel. According toone embodiment, for example, the fixing member may be a protrudingportion, and an accommodating member (e.g., a through hole or a blindhole) may be provided in the optical sheet or the liquid crystal panelfor accommodating the protruding member. The fixing member on the firstsurface may be a second guide for defining the position of the liquidcrystal panel. In such an embodiment, the second guide B may be disposedon the first surface at a predetermined position thereon as shown inFIG. 1.

The first guide A and, selectively, at least one of the second guide Band a third guide C may be connected to each other to form as a singleunitary and indivisible unit to define an integrated structure.According to one embodiment, for example, the first surface of theintegrated structure of the first guide and the second guide may supportthe liquid crystal panel. Alternatively, the first guide A and,selectively, at least one of the second guide B and the third guide Cmay be individual parts configured to be assembled. FIG. 1 shows anembodiment where the cross-section of the second guide B has a simplequadrangular shape, but it is not limited thereto, and may have variousshapes (e.g., to include various members for accommodating/fixing aliquid crystal panel), in an alternative embodiment.

In an embodiment, a strip is disposed on the second surface. In oneembodiment, for example, at least a portion of the second surface isprovided with a strip. In such an embodiment, the strip overlaps an edgeportion (a region adjacent to the edge) of a top surface of the opticalsheet or an edge portion of a top surface of the photoconversion layerwhen the optical sheet or the photoconversion layer is combined with themold frame. The strip may extend along an edge of the optical sheet oran edge of the photoconversion layer to overlap a region adjacent to theedge of the top surface of the optical sheet or the edge of the topsurface of the photoconversion layer.

According to one embodiment, for example, at least a portion of thebottom surface of the strip may face (e.g., touch) the edge portion ofthe top surface of the photoconversion layer, or may face (e.g., touch)the edge portion of the top surface of any one of the optical sheets.The second surface of the first guide A may fix or define the positionof the photoconversion layer, and the third surface of the first guide Amay fix or define the position of the optical sheets.

According to an embodiment, the third surface may have a step structure.Referring to FIG. 4 or FIG. 5, the third surface having a step maydefine (or fix) the position of at least one optical sheet using theupper or lower part of the step. According to one embodiment, forexample, the top surface of the lower part of the step may support thebottom surface of an optical sheet. In such an embodiment, the lowerpart of the step may protrude further than the upper part to support thebottom surface of the optical sheets.

According to another embodiment, the second surface may contact the topsurface of the optical sheets to define the position of thephotoconversion layer and the optical sheets disposed thereon.

The strip on the second surface may substantially decrease oreffectively prevent the light leakage (e.g., blue light leakage) at ascreen edge part of a flat panel display device, e.g., the liquidcrystal display device.

Many researches have been made to improve the display quality of adisplay device (e.g., a display device including a flat panel or acurved panel, or a flexible display device) by using a sheet including alight emitting material such as quantum dots. Some liquid crystaldisplay devices may use a combination of a light emitting diode (“LED”)emitting visible light, for example blue light, and a photoconversionsheet (including a light emitting material such as quantum dots) insteadof a white light source. However, in the case of a flat panel displaydevice using a photoconversion sheet, the blue light leakage phenomenontypically occurs in a screen edge part. Without being bound by anytheory, such blue light leakage phenomenon may occur due to scatteredblue light and a light circulation decrease at the edge part. Here, thescattered blue light is blue light emitted from the blue LED but notincident to the light guide panel (“LGP”) or the photoconversion sheet.The scattered blue light may not be effectively converted into whitecolor light by the photoconversion layer, and thus may cause the bluelight leakage at the screen edge part of a final display device.

The visible light emitted from an LED (e.g., a blue LED) may becirculated due to the presence of an optical sheet disposed on thephotoconversion sheet and a reflector formed on the bottom part of thedisplay device (and optionally disposed under the LGP), and suchcirculation may increase chances of encountering the quantum dots in thephotoconversion sheet for the blue light. However, the blue light have adecreased chance of circulation especially at the edge part, and thusthe photoconversion degree at the edge part becomes different from otherregions (e.g., a central region) of panel. The blue light leakage maycause a sharp increase in the color temperature of the screen edge part,resulting in deterioration of the color uniformity such that a user mayrecognize such deterioration in display quality.

In an embodiment, the mold frame may substantially or effectivelymitigate the blue light leakage phenomenon. In an embodiment, the moldframe includes a strip on the bottom surface (e.g., the second surfacein FIG. 1) of the first guide defining the position of thephotoconversion sheet, the display panel, or the like. In such anembodiment, the scattered blue light may be converted into light havinga longer wavelength by the strip. Alternatively, the strip may have areflective function or scattering/absorptive functions, allowing theblue light at the edge part to have more chances of light circulation.

According to one embodiment, the strip may include at least one of afilm including a polymer matrix and a light emitting material dispersedin the polymer matrix (hereinafter referred to as a photoconversionstrip), a reflective film, a film having a multi-layer structure, e.g.,a stacked film, including a light scattering layer and a lightabsorption layer on (e.g., disposed directly on or contacting) the lightscattering layer.

The strip may be disposed or provided on the second surface in apredetermined manner. In one embodiment, for example, the strip may beprovided on the second surface by spraying a composition having apredetermined composition or may be adhered on the second surface usingan additional adhesive agent (e.g., adhesives or a double-sided adhesivetape), but is not limited thereto.

In such an embodiment, types of the polymer matrix are not particularlylimited as long as it may be used as a host matrix for a light emittingmaterial (e.g., a plurality of light emitting particles). The polymermatrix may include a transparent polymer.

In one embodiment, for example, the polymer matrix may include athiol-ene resin (e.g., a polymerization product of a first monomerincluding at least two thiol (SH) groups at a terminal end and a secondmonomer including at least two carbon-carbon unsaturated bonds at aterminal end: see US Patent Publication No. 2012/0001217, the entirecontents of which are incorporated herein by reference), apoly(meth)acrylate-based resin, an epoxy resin, a urethane resin, anolefin-based resin, a vinyl-based resin (polystyrene, polyvinylpyrrolidone, or the like), a polyester, and silicone resin, but is notlimited thereto.

In such an embodiment, the light emitting material may include asemiconductor nanocrystal, an inorganic phosphor, an organic dye, or acombination thereof. The absorption wavelength and the light emittingwavelength of the light emitting material are not particularly limited,as long as the material may absorb blue light, or ultraviolet (“UV”)light, to emit light of a wavelength of lower energy than that of theabsorbed light (e.g., green light, red light, or the like).

The semiconductor nanocrystal (also known as a quantum dot) may emitlight, which may vary with a composition and a size of the quantum dot.In an embodiment, the semiconductor nanocrystal may include a GroupII-VI compound, a Group III-V compound, a Group IV-VI compound, a GroupIV compound or elementary substance, or a combination thereof.

In such an embodiment, the Group II-VI compound may include at least oneselected from a binary element compound selected from CdSe, CdTe, ZnS,ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, MgS, and a mixture thereof; aternary element compound selected from CdSeS, CdSeTe, CdSTe, ZnSeS,ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS,CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS, and a mixturethereof; and a quaternary element compound selected from HgZnTeS,CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS,HgZnSeTe, HgZnSTe, and a mixture thereof. In such an embodiment, theGroup III-V compound may include at least one selected from a binaryelement compound selected from GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs,AlSb, InN, InP, InAs, InSb, and a mixture thereof; a ternary elementcompound selected from GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs,AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, and a mixturethereof; and a quaternary element compound selected from GaAlNP,GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs,GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb, and a mixturethereof. In such an embodiment, the Group IV-VI compound may include atleast one selected from a binary element compound selected from SnS,SnSe, SnTe, PbS, PbSe, PbTe, and a mixture thereof; a ternary elementcompound selected from SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe,SnPbS, SnPbSe, SnPbTe, and a mixture thereof; and a quaternary elementcompound selected from SnPbSSe, SnPbSeTe, SnPbSTe, and a mixturethereof. In such an embodiment, the Group IV compound may include atleast one selected from an elementary substance selected from Si, Ge,and a mixture thereof; and a binary element compound selected from SiC,SiGe, and a mixture thereof.

In such an embodiment, the binary element compound, the ternary elementcompound, or the quaternary element compound may exist in a uniformconcentration in the semiconductor nanocrystal particle or partiallydifferent concentrations in a same particle. The semiconductornanocrystal may have a core/shell structure, in which a semiconductornanocrystal surrounds another semiconductor nanocrystal. The elements inthe shell may have a concentration gradient such that the concentrationthereof becomes gradually lower from the shell to the core. In anembodiment, the semiconductor nanocrystal may have a structure includinga semiconductor nanocrystal core and a multi-layer shell surrounding thecore. The multi-layer shell may have a two or more layered shellstructure. Each layer of the multi-layer shell may have a singlecomposition, or an alloy or concentration gradient.

In an embodiment, the semiconductor nanocrystal may have a structure inwhich the material composition for the shell has a higher energy bandgap than that of the core, thereby effectively showing the quantumconfinement effect. In an embodiment, where the semiconductornanocrystal has a multi-layered shell, the energy band gap of the shelldisposed on the exterior of the core is higher than the shell closer tothe core. The semiconductor nanocrystal may have an UV to infraredwavelength range.

In an embodiment, the semiconductor nanocrystal may have quantumefficiency of greater than or equal to about 50%, for example, greaterthan or equal to about 70%, and for another example, greater than orequal to about 90%. In such an embodiment, where the semiconductornanocrystal may have quantum efficiency in the aforementioned ranges,luminous efficiency of a device may be improved.

The semiconductor nanocrystal may have a full width at half maximum(“FWHM”) of a light emitting wavelength spectrum of less than or equalto about nanometers (nm), for example, less than or equal to about 40nm, or less than or equal to about 30 nm, without limitation. Thesemiconductor nanocrystal may have a particle diameter (in case of anon-spherical particle, the greatest length) in a range of about 1 nm toabout 100 nm. In one embodiment, for example, the semiconductornanocrystal may have a particle diameter (in case of a non-sphericalparticle, the greatest length) in a range of about 1 nm to about 20 nm.

Shapes of the semiconductor nanocrystal are not particularly limited andmay include any shape available in the art. In one embodiment, forexample, the semiconductor nanocrystal may be spherical, pyramidal,multi-armed, or cubic nanoparticles, nanotubes, nanowires, nanofibers,nanoplate, or the like.

The semiconductor nanocrystal may be synthesized according to any knownmethod or may be commercially available.

In an embodiment, where the light emitting material includes theinorganic phosphor, kinds or sizes of the inorganic phosphor are notparticularly limited if the inorganic phosphor is capable of absorbingblue light and emitting light having a desired wavelength. In oneembodiment, for example, the inorganic phosphor may be a nano-sizedinorganic phosphor. The inorganic phosphor may have any composition. Inone embodiment, for example, the inorganic phosphor may include garnetphosphors, silicate-based phosphors, sulfide-based phosphors, acidnitride phosphors, nitride phosphors, aluminate-based phosphors, or acombination thereof, but is not limited thereto. The garnet phosphorsmay include Y₃Al₅O₁₂:Ce³⁺ (YAG:Ce), Tb₃Al₅O₁₂:Ce³⁺ (TAG:Ce), or acombination thereof. The silicate-based phosphors may include(Sr,Ba,Ca)₂SiO₄:Eu²⁺, (Sr,Ba,Ca,Mg,Zn)₂Si(OD)₄:Eu²⁺ (wherein D=F, Cl, S,N, Br), Ba₂MgSi₂O₇:Eu²⁺, Ba₂SiO₄:Eu²⁺, Ca₃(Sc,Mg)₂Si₃O₁₂:Ce³⁺ or acombination thereof. The sulfide-based phosphors may include(Ca,Sr)S:Eu²⁺, (Sr,Ca)Ga₂S₄:Eu²⁺, or a combination thereof. The acidnitride phosphors may include SrSi₂O₂N₂:Eu²⁺, SiAlON:Ce³⁺,β-SiAlON:Eu²⁺, Ca-α-SiAlON:Eu²⁺, Ba₃Si₆O₁₂N₂:Eu²⁺, or a combinationthereof. The nitride phosphors may include CaAlSiN₃:Eu²,(Sr,Ca)AlSiN₃:Eu²⁺, Sr₂Si₅Na:Eu²⁺, or a combination thereof. Thealuminate-based phosphors may include (Sr,Ba)Al₂O₄:Eu²⁺,(Mg,Sr)Al₂O₄:Eu²⁺, BaMg₂Al₁₆O₂₇:Eu²⁺, or a combination thereof. Theinorganic phosphor may have any size, and may be, for example,nano-sized inorganic phosphors or micrometer sized inorganic phosphors.The inorganic phosphor may be synthesized according to any known methodor may be commercially available.

In an embodiment, where the light emitting material includes the organicdye, the organic dye may be an organic material dye having lightemitting characteristics, and kinds thereof are not particularlylimited. In one embodiment, for example, the organic dye may be anorganic fluorescent dye and/or an organic phosphorescent dye, but notbeing limited thereto. In one embodiment, for example, the organic dyemay be an organic metal complex or an organic material dye, but notbeing limited thereto. In one embodiment, the organic dye may be, forexample, an organic dye in a form of an organic metal complex such astris(2-phenylpyridine) iridium (“Ir(ppy)”), or an organic dye includingan organic material such as coumarin, rhodamine, phenoxazone, stilbene,terphenyl, or quarterphenyl. The organic dye may be synthesizedaccording to any synthesis method known in the art or may becommercially available.

In an embodiment, the concentration of the light emitting material(e.g., quantum dots, inorganic phosphor, or organic dye) in thephotoconversion strip may be controlled to adjust the color temperatureof an edge of a display screen of the display device to a desirablelevel. In an embodiment, the concentration of the light emittingmaterial (e.g., quantum dots, inorganic phosphor, or organic dye) in thephotoconversion strip is not particularly limited and may beappropriately selected in light of the types of polymer matrix, thetypes of light emitting material, the color temperature of the screenedge, or the thickness or to the width of the photoconversion strip, orthe like.

In another embodiment, the strip may include a reflective film. In oneembodiment, for example, the reflective film may include a scatteredreflective film or a specular reflective film. The reflective film mayhave light transmittance of less than about 10%, for example, less thanabout 9%, less than about 5%, or less than about 1%. The reflective filmmay be any reflective film available in the display field. In oneembodiment, for example, the reflective film may include the polymermatrix and an inorganic material (e.g., titanium dioxide particles,barium sulfate, or a combination thereof) dispersed in the polymermatrix. In one embodiment, For example, the specular reflective film mayinclude a silver deposit film, a multi-layered reflective film, ananodic aluminum oxide film, or the like, but is not limited thereto. Thescattered reflective film includes a polymer stretched film (e.g., whitepolyester biaxially oriented film (white polyester film), whitepolypropylene stretched film, or the like), but is not limited thereto.The reflective film may be fabricated by the known method or may becommercially available.

According to another embodiment, the strip may include a stacked filmincluding a light scattering layer and a light absorption layer disposeddirectly on the light scattering layer. In such an embodiment, The lightscattering layer may include silica, alumina, glass, calcium carbonate(CaCO₃), talc, mica, aluminum oxide, barium titanate, barium carbonate,barium sulfate, zinc oxide (ZnO), cerium oxide, titanium oxide,zirconium oxide (ZrO₂), aluminum hydroxide, and magnesium oxide (MgO),but is not limited thereto. The light scattering layer may be a polymerfilm including the aforementioned material, but is not limited thereto.In an embodiment, The light absorption layer may include carbon black, ablack dye, a black pigment, iron oxide, copper oxide, tin oxide, or amixture thereof. The light absorption layer may be a polymer layerincluding the aforementioned material. Types of the polymer for thelight scattering layer and the light absorption layer are notparticularly limited, and may be selected appropriately. In oneembodiment, for example, the polymer may be selected from the materialset forth above for the polymer matrix, but is not limited thereto. Inone embodiment, for example, the light absorption layer may include anacryl-based polymer resin coated with carbon black, a urethane-basedpolymer resin coated with carbon black, or a combination thereof. Insuch an embodiment, the strip may be disposed in the mold frame to allowthe light scattering layer to overlap the region adjacent to the edge ofthe top surface of the optical sheet or the top surface of thephotoconversion layer.

According to another alternative embodiment, the strip may include(e.g., be a combination of) at least two of a film including a polymermatrix and a light emitting material dispersed in the polymer matrix, areflective film, and a stacked film including a light scattering layerand a light absorption layer stacked on the light scattering layer. Inone embodiment, For example, the strip may be a hybrid film in which afilm (hereinafter, also called as photoconversion strip) including apolymer matrix and a light emitting material dispersed in the polymermatrix and a reflective film are arranged side by side. In oneembodiment, for example, the strip may have a form including at leasttwo of the photoconversion strip, the reflective film, and the stackedfilm that are arranged side by side (see FIG. 12). According to anotheralternative embodiment, the strip may have a stacked structure of thephotoconversion strip and the reflective film.

In an embodiment, as described above, the strip may substantiallymitigate or effectively prevent the light leakage (e.g., blue lightleakage) of the display device. In one embodiment, for example, thestrip may decrease the color temperature of the edge of the displaydevice. According to an embodiment, the strip may play a role ofdecreasing the color temperature of light emitted from the screen edgepart of the display device. The decrease in the color temperature may bemade to such an extent that in a curve plotting the color temperature(y-axis) over the position from the screen edge of the display device tothe center thereof (x-axis), the difference between the colortemperature of the screen center and the color temperature obtained byextrapolation with respect to the y-axis at the position having anaverage color temperature within 1 centimeter (cm) from the screen edgemay be less than or equal to about 5000 K, less than or equal to about4500 K, less than or equal to about 4000 K, less than or equal to about3500 K, or less than or equal to about 3000 K. According to oneembodiment, for example, the difference between the color temperature ofthe screen edge of the display and the color temperature of the screencenter thereof may be less than or equal to about 5000 K. Accordingly,an embodiment of the display device including the mold frame may haveimproved display quality.

In an embodiment, the color temperature at the screen edge may belowered to the desirable level (e.g., optimized level) by adjusting thefeatures or composition of the strip (e.g., by adjusting a concentrationof light emitting material, a thickness, or a width). The optimizedcolor temperature may be selected referring to the color temperature atthe center of the screen or the target color temperature of thecorresponding display.

According to an embodiment, a width of the region that is adjacent tothe edge of the top surface of the optical sheet or the top surface ofthe photoconversion layer and is overlapping the strip (hereinafter, theoverlapping region) is not particularly limited and may be appropriatelyselected in light of the type of the strip, type of the display panel, adesired color temperature of the edge part, or the like. In oneembodiment, For example, the width of overlapping region may be lessthan about 5 millimeters (mm), but is not limited thereto. In anembodiment, the thickness of the strip is not particularly limited andmay be appropriately selected considering the type of strip, the displaytype, and the desired color temperature of the edge part. In oneembodiment, For example, the strip may have a thickness of less than orequal to about 10 mm, less than or equal to about 5 mm, or less than orequal to about 1 mm, but is not limited thereto.

The mold frame may further include a cover part for covering an LEDlight source or a light guide plate under the first guide A or the thirdguide C, but is not limited thereto.

Detailed features, e.g., the shape and material, of the cover part areknown in the art, and are not particularly limited.

In one embodiment, for example, each member constituting the mold framemay be made of an injection-moldable plastic material (e.g.,polyethylene terephthalate, polyethylene, polycarbonate, polyurethane,polypropylene, acrylonitrile butadiene styrene (“ABS”) resin, orpolystyrene), but it is not limited thereto.

According to another embodiment, the backlight unit may include:

a light source;

a photoconversion layer spaced apart from the light source and whichconverts light incident from the light source to white light and emitsthe converted light to a liquid crystal panel;

an optical sheet disposed on the photoconversion layer; and

an embodiment of the mold frame according to the invention.

In an embodiment, the light source may be an LED light source, but isnot limited thereto. The LED light source includes a plurality of LEDchips that emits light having a predetermined wavelength. The LED lightsource may be an LED light source that emits blue light or an LED lightsource that emits UV rays.

The backlight unit may be an edge type backlight unit further includinga light guide panel disposed between the light source and thephotoconversion layer. The light guide panel may increase uniformity oflight from the light source and transmitted to the display area, and mayinclude a transparent acrylic plate. In one embodiment, for example, aplurality of dots or V-holes may be formed on the lower surface of thelight guide panel to uniformly reflect light, but not being limitedthereto. The rear side of the light guide panel may be provided with areflector. The reflector is a plate having high light reflectance, andmay decrease the light loss by back-reflecting light incident from therear side of light guide panel to the light guide side. Alternatively,the backlight unit may be a direct lighting type without a light guidepanel. The direct lighting backlight unit is also known in the art, andany detailed description thereof will be omitted.

In an embodiment, the photoconversion layer is spaced apart from thelight source at a predetermined distance, and converts light emittedfrom the light source to white light and emits the light toward theliquid crystal panel (not shown). According to one embodiment, forexample, the photoconversion layer may include a polymer matrix and asemiconductor nanocrystal dispersed in the polymer matrix. The types ofpolymer matrix and the types of semiconductor nanocrystal for providinga photoconversion layer and the method of manufacturing thephotoconversion layer are known in the art, and are not particularlylimited. In one embodiment, For example, the photoconversion layer mayinclude the polymer matrix and the semiconductor nanocrystal, asdescribed above.

When the light emitted from the light source is passed through thephotoconversion layer, blue light, green light and red light are mixedto provide white light. In an embodiment, the photoconversion layer mayinclude a plurality of layers. In such an embodiment, the plurality oflayers may be disposed in such a manner that each of them has a lightemitting wavelength with lower energy toward the LED light source. Inone embodiment, for example, where the LED light source is a blue LEDlight source, the photoconversion layer may include a redphotoconversion layer and a green photoconversion layer which aresequentially stacked in a direction away from the LED light source.

In an embodiment, an optical sheet may be disposed on thephotoconversion layer, and the optical sheet may include at least one ofa diffusion plate, a prism sheet, a microlens sheet, and a luminanceimprovement film (e.g., a double brightness enhancement film (“DBEF”)),but is not limited thereto.

FIG. 6 shows an embodiment of a backlight unit, where a photoconversionstrip is disposed on the second surface of a mold frame. In such anembodiment, the mold frame is substantially the same as the mold framedescribed above. The photoconversion strip may be a film including apolymer matrix and a semiconductor nanocrystal, an inorganic phosphor,an organic dye, or a combination thereof dispersed in the matrix. Thephotoconversion strip may enhance the white light at the edge partshowing insufficient photoconversion otherwise and may increase thelight conversion efficiency of the edge part. In addition, the inherentcolor gamut of the light emitting material (e.g., a semiconductornanocrystal) may be maintained at the edge part. In addition, as thelight conversion efficiency may increase at the edge part in thedisplay, the average luminance and light uniformity may also be enhancedin the entire screen of the display.

According to one embodiment, for example, the photoconversion strip mayhave the same composition as that of the photoconversion layer.

FIG. 7 shows an alternative embodiment of a backlight unit, where thepolymer film including a reflective material is provided as a strip onthe second surface of the mold frame. In such an embodiment, the lighthas an increased chance of circulation such that efficiency ofphotoconversion may be substantially improved.

FIG. 8 shows an alternative embodiment of a backlight unit, where thesecond surface of the mold frame includes a stacked film including alight scattering layer and a light absorption layer stacked on the lightscattering layer. In such an embodiment, the scattered blue light hasincreased chances of encountering with the quantum dots in thephotoconversion layer, and the light absorption layer may furthersuppress the blue light leakage.

According to another embodiment, the liquid crystal display includes:

a liquid crystal panel;

the backlight unit irradiating light to the liquid crystal panel; and

a mold frame.

In such an embodiment, the mold frame and the back light unit aresubstantially the same as those in embodiments described above, and anyrepetitive detailed description thereof will be omitted. In such anembodiment, the liquid crystal panel is not particularly limited, andmay include any known or commercially available liquid crystal panel.

FIG. 9 to FIG. 11 schematically show cross-sectional views ofembodiments of the liquid crystal display.

In an embodiment, as shown in FIG. 9, the liquid crystal display mayinclude a fixing member for fixing an optical sheet on the first surfaceof the first guide A, and a through hole or a blind hole foraccommodating the fixing member may be defined or formed through theoptical sheet. In such an embodiment of the liquid crystal display shownin FIG. 9, the first surface supports the optical sheet, and the opticalsheet supports the liquid crystal panel. The fixing member may extend tofix the position of the liquid crystal panel as well as the opticalsheet. In an embodiment, as shown in FIG. 9, the second surface of thefirst guide defines the position of the photoconversion layer or sheet.In such an embodiment, the strip on the second surface is substantiallythe same as that of embodiments described above, and any repetitivedetailed description thereof will be omitted. In such an embodiment, thestrip may be disposed to overlap an edge of the photoconversion sheet.

FIG. 10 is a cross-sectional view schematically showing an alternativeembodiment of the liquid crystal display. Referring to FIG. 10, in anembodiment, the first surface of the first guide A supports the liquidcrystal panel. In such an embodiment, the second guide B is disposed orprovided adjacent to the edge of the liquid crystal panel, but is notlimited thereto. According to another alternative embodiment, the secondguide B may be a fixing member disposed on the first surface of thefirst guide A. In such an embodiment, the liquid crystal panel may havea recessed portion for accommodating the fixing member on the bottomsurface. In an embodiment, as shown in FIG. 10, the second surface ofthe first guide defines the position of the optical sheet and thephotoconversion sheet. In such an embodiment, the strip disposed on thesecond surface is substantially the same as that of embodimentsdescribed above, and any repetitive detailed description thereof will beomitted. In such an embodiment, the strip is disposed to overlap theedge of the top surface of optical sheet. While not in contact with thephotoconversion sheet, the strip also overlaps with an edge of thephotoconversion sheet.

FIG. 11 is a cross-sectional view schematically showing anotheralternative embodiment of a liquid crystal display. Referring to FIG.11, in an embodiment, the first surface of the first guide A supportsthe liquid crystal panel. The third surface of first guide A forms astep, and a surface of the third surface facing the liquid crystal panelmay support the optical sheet and may include a fixing member for fixingthe optical sheet. In an embodiment, as shown in FIG. 11, the secondsurface of first guide defines the position of the photoconversionsheet. In such an embodiment, the strip disposed on the second surfaceis substantially the same as that of embodiments described above, andany repetitive detailed description thereof will be omitted. In such anembodiment, the strip is disposed to contact and overlap the edge ofphotoconversion sheet.

According to another alternative embodiment, the liquid crystal displaymay further include the photoconversion sheet including a polymer matrixand a semiconductor nanocrystal (including quantum dots), an inorganicphosphor, or a combination thereof dispersed in the polymer matrix, andthe strip is disposed on one side surface of the photoconversion sheetand extending along the edge of at least a part of the photoconversionsheet. The strip may protrude from the edge of the photoconversion sheetto define a step. The strip may extend along the entire edge of thephotoconversion sheet. The photoconversion sheet may be a quantumdot-included sheet. In such an embodiment, the polymer matrix, thesemiconductor nanocrystal, the inorganic phosphor and the strip aresubstantially the same as those in embodiments described above, and anyrepetitive detailed description thereof will be omitted.

Hereinafter, embodiments will be described in greater detail withreference to examples.

EXAMPLES Example 1

A reflective film strip having a total width of 7 mm (total length: 40cm), a phosphor-included strip having a total width of 7 mm (totallength: 40 cm) and a quantum dot-included strip having a total width of7 mm (total length: 40 cm) are prepared, and the color temperaturedifference between a center part of a display screen (hereinafter,screen center part) and an edge part of the display screen (hereinafter,screen edge part) is measured before and after the strip is attached toform the liquid crystal display device shown in FIG. 11.

The reflective film strip is a white polyethylene terephthalate (“PET”)film (manufacturer: SKC, trade name: SY90) having a thickness of 300micrometers (μm), and the region overlapping the photoconversion layeris 2 mm width.

The phosphor-included photoconversion strip is a 200 μm-thick film thatincludes a plurality of inorganic phosphors (Y₃AlsO₁₂:Ce³⁺ (YAG:Ce))having a size of about 10 μm in a polymer matrix (e.g., the polymermatrix described above) (in an amount of 8 gram of the inorganicphosphors per 100 gram of the polymer matrix), and the regionoverlapping the photoconversion layer has a width of 2 mm.

The photoconversion strip including quantum dots is a 200 μm-thick filmthat includes InP/ZnS quantum dots in the polymer matrix (in an amountof 1 gram of the QDs per 100 gram of the polymer matrix), and the regionoverlapping the photoconversion layer has a width of 2 mm.

The strip is attached to the second surface of the mold frame using adouble-sided adhesive tape.

Before and after the strips are attached, the Cx value, the Cy value,the color temperature of the screen edge, and the difference between thecolor temperature of the screen center part and the color temperature ofthe screen edge part are measured by using CS-2000 equipmentmanufactured by Konica Minolta (at a measuring angle of 1 degree), andthe results are shown in the following Table 1.

TABLE 1 When being equipped with a 7 mm-width strip on an edge parthaving a color temperature difference of 10,000K (T) or more relative tothe center Center Reflective film 7 mm Before After Before After beingbeing being being equipped equipped Δ equipped equipped Δ Cx 0.276 0.2780.003 0.255 0.273 0.018 Cy 0.278 0.283 0.005 0.238 0.261 0.023 T 1140010644 −756 43333 14044 −29289 ΔT 31933 3400 (relative to the center)Phosphor film 7 mm Quantum dot film 7 mm Before After Before After beingbeing being being equipped equipped Δ equipped equipped Δ Cx 0.256 0.2850.029 0.258 0.282 0.024 Cy 0.242 0.289 0.047 0.243 0.284 0.041 T 333339516 −23817 30000 10111 −19889 ΔT 21933 −1128 18600 −533 (relative tothe center)

Table 1 shows that the Cx and Cy values are not substantially changedbefore and after being equipped with the strip, which implies thatinstalling the strip does not have an substantial effect on the whitebalance of the liquid crystal display.

As shown in Table 1, the difference between the color temperature of thescreen center part and the color temperature of the screen edge part is31933 K before the reflective strip being attached, but the differencebetween the color temperature of the screen center part and the colortemperature of the screen edge part is 3400 K after the reflective stripbeing attached.

It is also shown that the difference between the color temperature ofthe screen center part and the color temperature of the screen edge partis 21933 K before the phosphor-included strip being attached, and thedifference between the color temperature of the screen center part andthe color temperature of the screen edge part is 1128 K after thephosphor-included strip being attached.

It is also shown that the difference between the color temperature ofthe screen center part and the color temperature of the screen edge partis 18600 K before the strip including quantum dots are attached, and thedifference between the color temperature of the screen center part andthe color temperature of the screen edge part is 533 K after the stripincluding quantum dots are attached.

Example 2

A reflective film strip having a total width of 5 mm (total length: 5800cm), a phosphor-included strip having a total width of 5 mm (totallength: 5800 cm), and a quantum dot-included strip having a total widthof 5 mm (total length: 5800 cm) are prepared, and the color temperaturedifference between the screen center part and the screen edge part ismeasured before and after the strips are attached to an edge of theliquid crystal display device shown in FIG. 11.

The reflective film strip is a white PET film (manufacturer. SKC, tradename: SY90) having a thickness of 300 μm, and the region overlapping thephotoconversion layer is 2 mm width.

The photoconversion strip including phosphors is a 200 μm-thick filmthat includes an inorganic phosphor (Y₃Al₅O₁₂:Ce³⁺ (YAG:Ce)) having asize of about 10 μm (in an amount of 8 gram of the inorganic phosphorsper 100 gram of the polymer matrix) in the polymer matrix, and theregion overlapping the photoconversion layer has a width of 2 mm.

The photoconversion strip including quantum dots is a 200 μm-thick filmthat includes InP/ZnS quantum dots (in an amount of 1 gram of the QDsper 100 gram of the polymer matrix) in the polymer matrix, and theregion overlapping the photoconversion layer has a width of 2 mm.

The strip is attached to the second surface of the mold frame using adouble-sided adhesive tape.

Before and after the strips are attached, the Cx value, the Cy value,the color temperature of the screen edge, and the difference between thecolor temperature of the screen center part and the color temperature ofthe screen edge part are measured by using CS-2000 equipmentmanufactured by Konica Minolta (at a measuring angle of 1 degree), andthe results are shown in the following Table 2.

TABLE 2 When being equipped with 5 mm-width strip on an edge part havingcolor a temperature difference of 10,000K (T) or less relative to thecenter Center Reflective film 5 mm Before After Before After being beingbeing being equipped equipped Δ equipped equipped Δ Cx 0.276 0.278 0.0030.263 0.276 0.013 Cy 0.278 0.283 0.005 0.256 0.272 0.016 T 11400 10644−756 18382 11971 −6411 ΔT 6982 1327 (relative to the center) Phosphorfilm 5 mm Quantum dot film 5 mm Before After Before After being beingbeing being equipped equipped Δ equipped equipped Δ Cx 0.263 0.280 0.0170.264 0.282 0.018 Cy 0.257 0.271 0.015 0.258 0.275 0.017 T 17996 11262−6734 17380 10730 −6650 ΔT 6596 618 5980 86 (relative to the center)

Table 2 shows that the Cx and Cy values are not substantially changedbefore and after being equipped with the strip, which implies thatinstalling the strip does not have a substantial effect on the whitebalance of the liquid crystal display.

As shown in Table 2, the difference between the color temperature of thescreen center part and the color temperature of the screen edge part is6982 K before the reflective strip being attached, but the differencebetween the color temperature of the screen center part and the colortemperature of the screen edge part is 1327 K after the reflective stripbeing attached.

It is also shown that the difference between the color temperature ofthe screen center part and the color temperature of the screen edge partis 6596 K before the phosphor-included strip being attached, and thedifference between the color temperature of the screen center part andthe color temperature of the screen edge part is 618 K after thephosphor-included strip being attached.

It is also shown that the difference between the color temperature ofthe screen center part and the color temperature of the screen edge partis 5980 K before the strip including quantum dots are attached, and thedifference between the color temperature of the screen center part andthe color temperature of the screen edge part is 86 K after the stripincluding quantum dots are attached.

While the inventive principle has been described in connection with whatpresently considered to be practical exemplary embodiments, it is to beunderstood that the inventive scope is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. A mold frame comprising: a first guide whichdefines a position of a photoconversion layer or a position of anoptical sheet disposed on the photoconversion layer; and a stripdisposed on the first guide, wherein the first guide comprises: a firstsurface defined to face a liquid crystal panel; a second surfaceopposite to the first surface; and to a third surface extending from anedge of first surface to an edge of second surface, wherein the strip isdisposed on the second surface, wherein the strip contacts an edgeportion of a top surface of the photoconversion layer when the opticalsheet or the photoconversion layer is combined with the mold frame,wherein the strip comprises at least one of: a film comprising a polymermatrix and a light emitting material dispersed in the polymer matrix,wherein the light emitting material comprises a semiconductornanocrystal, an inorganic phosphor, an organic dye or a combinationthereof; a reflective film comprising a polymer stretched film; and astacked film comprising a light scattering layer and a light absorptionlayer on the light scattering layer.
 2. The mold frame of claim 1,wherein the strip is configured to lower a color temperature of an edgeof a display screen and, whereby a color temperature difference betweena center and the edge portion of the display screen is less than orequal to about 5000K.
 3. The mold frame of claim 1, wherein the firstsurface supports the liquid crystal panel, and the mold frame furthercomprises at least one of: a second guide disposed on the first guideand which defines a position of the liquid crystal panel; and a thirdguide disposed under the first guide and which further defines theposition of the photoconversion layer or the position of the opticalsheet.
 4. The mold frame of claim 1, wherein the second surface definesthe position of the photoconversion layer, and the third surface definesthe position of the optical sheet.
 5. The mold frame of claim 4, whereinthe third surface has a step, and an upper part of the step or a lowerpart of the step defines the position of the optical sheet.
 6. The moldframe of claim 5, wherein the lower part of the step protrudes furtherthan the upper part of the step and supports a bottom surface of theoptical sheet.
 7. The mold frame of claim 1, wherein at least a portionof a bottom surface of the strip faces the edge portion of the topsurface of the photoconversion layer or faces the edge portion of thetop surface of the optical sheet.
 8. The mold frame of claim 1, whereinto the strip comprises the film comprising the polymer matrix and thelight emitting material dispersed in the polymer matrix, and the polymermatrix comprises a thiol-ene resin, a poly(meth)acrylate-based resin, anepoxy resin, a silicone resin, a urethane resin, an olefin resin,polyvinyl, polyester, or a combination thereof.
 9. The mold frame ofclaim 1, wherein the reflective film comprises a white polyester film, awhite polypropylene film, or a combination thereof.
 10. The mold frameof claim 1, wherein the reflective film has a light transmittance ofless than about 10%.
 11. The mold frame of claim 1, wherein the stripcomprises the stacked film comprising the light scattering layer and thelight absorption layer on the light scattering layer, the lightscattering layer comprises a polymer layer comprising at least oneselected from silica, alumina, glass, calcium carbonate (CaCO₃), talc,mica, aluminum oxide, barium titanate, barium carbonate, barium sulfate,zinc oxide (ZnO), cerium oxide, titanium oxide, zirconium oxide (ZrO₂),aluminum hydroxide, and magnesium oxide (MgO), the light absorptionlayer comprises a polymer layer comprising carbon black, a black dye, ablack pigment, iron oxide, copper oxide, tin oxide, or a combinationthereof, and the light scattering layer overlaps the edge portion of thetop surface of the optical sheet or the edge portion of the top surfaceof the photoconversion layer when the optical sheet or thephotoconversion layer is combined with the mold frame.
 12. The moldframe of claim 1, wherein the strip covers an entire of the secondsurface.
 13. The mold frame of claim 1, wherein the strip has athickness of less than or equal to about 10 millimeters.
 14. A backlightunit comprising: a light source which emits light; a photoconversionlayer spaced apart from the light source and which converts the lightincident thereto from the light source to white light and emits thewhite light; and a strip overlapping an edge portion of thephotoconversion layer, wherein the strip comprises at least one of: afilm comprising a polymer matrix and a light emitting material dispersedin the polymer matrix, wherein the light emitting material comprises asemiconductor nanocrystal, an inorganic phosphor, an organic dye or acombination thereof; a reflective film comprising a polymer stretchedfilm; and a stacked film comprising a light scattering layer and a lightabsorption layer on the light scattering layer.
 15. The backlight unitof claim 14, wherein the strip is configured to lower a colortemperature of an edge of a display screen and, whereby a colortemperature difference between a center and the edge portion of thedisplay screen is less than or equal to about 5000K.
 16. The backlightunit of claim 14, wherein the strip is a photoconversion strip.
 17. Thebacklight unit of claim 16, wherein the photoconversion strip contactsthe edge portion of the photoconversion layer.
 18. The backlight unit ofclaim 16, further comprising an optical sheet disposed over thephotoconversion layer.
 19. The backlight unit of claim 14, furthercomprising a mold frame and wherein the strip is disposed between themold frame and the edge portion of the photoconversion layer.
 20. Thebacklight unit of claim 19, wherein the strip is attached to the moldframe.
 21. The backlight unit of claim 19, wherein the strip is aphotoconversion strip.
 22. The backlight unit of claim 21, wherein thephotoconversion strip contacts the edge portion of the photoconversionlayer.
 23. A liquid crystal display comprising: a liquid crystal panel;and a backlight unit which provides light to the liquid crystal panel;wherein the backlight unit comprises: a light source comprising a bluelight emitting diode; a photoconversion layer spaced apart from thelight source and which converts light incident from the blue lightemitting diode of the light source to white light and emits the whitelight; a strip overlapping an edge portion of a photoconversion layer,wherein the strip comprises at least one of: a film comprising a polymermatrix and a light emitting material dispersed in the polymer matrix,wherein the light emitting material comprises a semiconductornanocrystal, an inorganic phosphor, an organic dye or a combinationthereof; a reflective film comprising a polymer stretched film; and astacked film comprising a light scattering layer and a light absorptionlayer on the light scattering layer.
 24. The liquid crystal display ofclaim 23, wherein the strip is configured to lower a color temperatureof an edge of a display screen, whereby a color temperature differencebetween a center and the edge portion of the display screen is less thanor equal to about 5000K.
 25. The liquid crystal display of claim 23,wherein the strip is a photoconversion strip.
 26. The liquid crystaldisplay of claim 23, wherein the photoconversion strip contacts the edgeportion of the photoconversion layer.
 27. The liquid crystal display ofclaim 23, further comprising an optical sheet disposed over thephotoconversion layer.
 28. The liquid crystal display of claim 23,further comprising a mold frame and wherein the strip is disposedbetween the mold frame and the edge portion of the photoconversionlayer.
 29. The liquid crystal display of claim 28, wherein the strip isattached to the mold frame.
 30. The liquid crystal display of claim 28,wherein the strip is a photoconversion strip.
 31. The liquid crystaldisplay of claim 30, wherein the photoconversion strip contacts the edgeportion of the photoconversion layer.
 32. A photoconversion sheetcomprising: a polymer matrix; and a light emitting material dispersed inthe polymer matrix, wherein the light emitting material comprises asemiconductor nanocrystal, an inorganic phosphor, an organic dye or acombination thereof, wherein a strip is disposed on a surface of thephotoconversion sheet along an edge portion thereof, and wherein thestrip comprises at least one of: a film comprising a polymer matrix anda light emitting material dispersed in the polymer matrix, wherein thelight emitting material comprises a semiconductor nanocrystal, aninorganic phosphor, an organic dye or a combination thereof; areflective film comprising a polymer stretched film; and a stacked filmcomprising a light scattering layer and a light absorption layer on thelight scattering layer.
 33. The photoconversion sheet of claim 32,wherein the strip is configured to lower a color temperature of an edgeof a display screen, whereby a color temperature difference between acenter and the edge portion of the display screen is less than or equalto about 5000K.
 34. The photoconversion sheet of claim 32, wherein thestrip protrudes from the edge portion to define a step structure. 35.The photoconversion sheet of claim 32, wherein the strip extends alongan entire edge of the photoconversion sheet.